Trying to measure outside (Columbus, OH)

[fatmarley]

Re: Trying to measure outside (Columbus, OH)

It's a lot easier to use a backyard, unless the ambient levels are 60dB or more. Otherwise it's not a problem to measure at 30dB or more above ambient even at 2 to 4 meters.

My problem is finding a large flat area with access to a power supply for my amplifier.

Do think a school sports hall is a bad idea for ground plane measurements?

Our back garden isn't very flat and it's also grass (I read somewhere that grass isn't good for ground plane measurements). If I bury my speakers flush with the ground (girlfriend will kill me but i'm getting desperate for some descent measurements) and suspend the microphone above (I could hang it from the washing line) - How much room from boundarys do I need to get good low frequency measurements? And more importantly, do you think it would work?

EDIT: With the speakers buried in the ground, could I line up the mic with the tweeter and measure the individual drivers for a full set of measurements for crossover design purposes? (EDIT AGAIN: obviously not because it wouldn't account for baffle step - In my defence it was around 2am when I wrote this and I wasn't thinking straight)

[billfitzmaurice]

Re: Trying to measure outside (Columbus, OH)

I was thinking of hiring a school sports hall to do ground plane measurements.

It's a lot easier to use a backyard, unless the ambient levels are 60dB or more. Otherwise it's not a problem to measure at 30dB or more above ambient even at 2 to 4 meters.

[fatmarley]

Re: Trying to measure outside (Columbus, OH)

I was thinking of hiring a school sports hall to do ground plane measurements.

[billfitzmaurice]

Re: Trying to measure outside (Columbus, OH)

Here is a measurement with the amp turned off so all I get is ambient noise:
What are they? Crickets? Cicadas? I should probably know, but right now I just want them to be quiet... Maybe earlier in the day I'll have more luck

The lows are probably traffic, perhaps miles away. The highs are mostly insects. But if you measure at a level 30dB or more above ambient you'll mask it out.

Sounds kind of crazy but you should get a hold of a local high school that has an auditorium that you could use in the afternoon/after class to do your testing

Then you'll end up measuring the room response, which is seldom good in a school. A few years back some 'experts' at the PSW forum held a subwoofer shootout in an old warehouse and couldn't figure out why the subs all showed the same peaks and valleys in their response, until a real expert pointed out that what they'd mostly measured was the room modes. :rolleyes:

[jonpike]

Re: Trying to measure outside (Columbus, OH)

"Here's the frequency response graph of my angry, not quite fully awake neighbor..."

I understand... been trying the outside measuring thing, too. Amazing how many noise sources there can be. Crows in the nearby tree, planes, wind.. wind chimes... you name it! And Murphy, waiting till you're starting the next one, to cue up the next gust...

[weinstro]

Re: Trying to measure outside (Columbus, OH)

Well, I suppose it turns out that the speaker's proximity to the mic actually makes the background noises almost irrelevant

Here are some of my measurements this evening:

[ATTACH=CONFIG]39276[/ATTACH]

You could try measuring very early in the morning.

[critofur]

Re: Trying to measure outside (Columbus, OH)

Well, I suppose it turns out that the speaker's proximity to the mic actually makes the background noises almost irrelevant

Here are some of my measurements this evening:

[Thumper Tom]

Re: Trying to measure outside (Columbus, OH)

Sounds kind of crazy but you should get a hold of a local high school that has an auditorium that you could use in the afternoon/after class to do your testing

[critofur]

Here is a measurement with the amp turned off so all I get is ambient noise:






Argh!!! Noisy buggers - anybody got a tanker truck full of non-toxic to humans bug killing spray? They are so loud, even playing music turned up high is half-way drowned out by these suckers!

What are they? Crickets? Cicadas? I should probably know, but right now I just want them to be quiet... Maybe earlier in the day I'll have more luck